#!/usr/bin/env python3
#
# ntfy-bell - run a command, forwarding OSC 9 notifications and BEL to ntfy
#
# Usage:
#   ntfy-bell <command> [args...]

import fcntl
import os
import pty
import select
import shlex
import shutil
import signal
import sys
import termios
import time
import tty
import urllib.request
from typing import Optional

BEL = 0x07
OSC9_PREFIX = b"\x1b]9;"  # ESC ] 9 ;
ST = b"\x1b\\"  # ESC \\ (string terminator)


def notify_ntfy(topic: str, title: str, message: str) -> None:
    url = f"https://ntfy.sh/{topic}"
    data = message.encode("utf-8", errors="replace")

    req = urllib.request.Request(url, data=data, method="POST")
    req.add_header("Title", title)

    with urllib.request.urlopen(req, timeout=5):
        pass


def _extract_osc9_from_buffer(buf: bytearray) -> Optional[str]:
    start = buf.find(OSC9_PREFIX)
    if start == -1:
        if len(buf) > 65536:
            del buf[:-4096]
        return None

    if start > 0:
        del buf[:start]

    payload_start = len(OSC9_PREFIX)
    bel_pos = buf.find(bytes([BEL]), payload_start)
    st_pos = buf.find(ST, payload_start)

    end_pos: Optional[int] = None
    term_len = 0

    if bel_pos != -1 and (st_pos == -1 or bel_pos < st_pos):
        end_pos = bel_pos
        term_len = 1
    elif st_pos != -1:
        end_pos = st_pos
        term_len = len(ST)

    if end_pos is None:
        if len(buf) > 65536:
            del buf[:-4096]
        return None

    payload = bytes(buf[payload_start:end_pos])
    del buf[: end_pos + term_len]

    return payload.decode("utf-8", errors="replace").strip("\r\n")


def _build_child_argv(cmd: list[str]) -> list[str]:
    cmd0 = cmd[0]

    if "/" in cmd0:
        return cmd

    if shutil.which(cmd0):
        return cmd

    shell = os.environ.get("SHELL") or "/bin/sh"
    shell_name = os.path.basename(shell)
    joined = shlex.join(cmd)

    if shell_name == "zsh":
        shell_cmd = (
            'source "${ZDOTDIR:-$HOME}/.zshrc" >/dev/null 2>&1; '
            f"eval {shlex.quote(joined)}"
        )
        return [shell, "-c", shell_cmd]

    return [shell, "-ic", joined]


def _copy_winsize(src_fd: int, dst_fd: int) -> None:
    try:
        winsize = fcntl.ioctl(src_fd, termios.TIOCGWINSZ, b"\0" * 8)
        fcntl.ioctl(dst_fd, termios.TIOCSWINSZ, winsize)
    except OSError:
        pass


def main() -> int:
    topic = os.environ.get("BELL2NTFY_TOPIC")
    if not topic:
        print("Error: environment variable BELL2NTFY_TOPIC not set", file=sys.stderr)
        return 2

    if len(sys.argv) < 2:
        print(f"usage: {sys.argv[0]} <command> [args...]", file=sys.stderr)
        return 2

    cmd = sys.argv[1:]
    child_argv = _build_child_argv(cmd)

    pid, master_fd = pty.fork()
    if pid == 0:
        try:
            os.execvp(child_argv[0], child_argv)
        except FileNotFoundError:
            print(f"{cmd[0]}: command not found", file=sys.stderr)
            os._exit(127)
        except PermissionError:
            print(f"{cmd[0]}: permission denied", file=sys.stderr)
            os._exit(126)

    stdin_fd = None
    stdin_is_tty = sys.stdin.isatty()
    old_tty_attrs = None
    old_winch_handler = None

    try:
        stdin_fd = sys.stdin.fileno()
    except OSError:
        stdin_fd = None

    if stdin_fd is not None and stdin_is_tty:
        try:
            old_tty_attrs = termios.tcgetattr(stdin_fd)
            tty.setraw(stdin_fd)
        except termios.error:
            old_tty_attrs = None

        _copy_winsize(stdin_fd, master_fd)

        def _on_winch(_signum: int, _frame: object) -> None:
            _copy_winsize(stdin_fd, master_fd)
            try:
                os.kill(pid, signal.SIGWINCH)
            except OSError:
                pass

        old_winch_handler = signal.getsignal(signal.SIGWINCH)
        signal.signal(signal.SIGWINCH, _on_winch)

    osc_last_sent = 0.0
    bel_last_sent = 0.0
    cooldown_s = 1.5
    parse_buf = bytearray()
    stdin_eof_sent = False

    try:
        while True:
            read_fds = [master_fd]
            if stdin_fd is not None:
                read_fds.append(stdin_fd)

            try:
                rlist, _, _ = select.select(read_fds, [], [])
            except InterruptedError:
                continue

            if stdin_fd is not None and stdin_fd in rlist:
                try:
                    user_data = os.read(stdin_fd, 4096)
                except OSError:
                    user_data = b""

                if user_data:
                    try:
                        os.write(master_fd, user_data)
                    except OSError:
                        break
                else:
                    if not stdin_is_tty and not stdin_eof_sent:
                        try:
                            os.write(master_fd, b"\x04")
                        except OSError:
                            pass
                        stdin_eof_sent = True
                    stdin_fd = None

            if master_fd in rlist:
                try:
                    data = os.read(master_fd, 4096)
                except OSError:
                    break

                if not data:
                    break

                try:
                    os.write(sys.stdout.fileno(), data)
                except OSError:
                    break

                parse_buf.extend(data)

                while True:
                    msg = _extract_osc9_from_buffer(parse_buf)
                    if msg is None:
                        break

                    now = time.time()
                    if now - osc_last_sent >= cooldown_s:
                        osc_last_sent = now
                        try:
                            notify_ntfy(
                                topic=topic,
                                title="Terminal notification",
                                message=msg if msg else f"OSC 9 notification from: {' '.join(cmd)}",
                            )
                        except Exception:
                            pass

                if bytes([BEL]) in data and parse_buf.find(OSC9_PREFIX) == -1:
                    now = time.time()
                    if now - bel_last_sent >= cooldown_s:
                        bel_last_sent = now
                        try:
                            notify_ntfy(
                                topic=topic,
                                title="Terminal bell",
                                message=f"BEL from: {' '.join(cmd)}",
                            )
                        except Exception:
                            pass

    finally:
        if stdin_fd is not None and stdin_is_tty and old_tty_attrs is not None:
            try:
                termios.tcsetattr(stdin_fd, termios.TCSADRAIN, old_tty_attrs)
            except termios.error:
                pass

        if old_winch_handler is not None:
            signal.signal(signal.SIGWINCH, old_winch_handler)

        try:
            os.close(master_fd)
        except OSError:
            pass

    _, status = os.waitpid(pid, 0)

    if os.WIFEXITED(status):
        return os.WEXITSTATUS(status)

    if os.WIFSIGNALED(status):
        return 128 + os.WTERMSIG(status)

    return 1


if __name__ == "__main__":
    raise SystemExit(main())